Method of manufacturing satchel bottom bags



Dec. 22, 1970 E.' KUGLER METHOD OF MANUFACTURING SATCHEL BOTTOM BAGS Filed March 6, 1966 INVEN'IOR.

[MA/Vail Myzze United States Patent 3,549,451 METHOD OF MANUFACTURING SATCHEL BOTTOM BAGS Emanuel Kugler, 124 Richmond Place, Lawrence, N.Y. 11559 Filed Mar. 6, 1968, Ser. No. 710,913 Int. Cl. B29c 27/02 US. Cl. 156-272 8 Claims ABSTRACT OF THE DISCLOSURE A method of economically mass producing a plastic satchel bottom bag from a conventional bottom gusset bag by eliminating, as by burning away, triangular end portions of the bottom gusset to provide the bag with a satchel bottom construction.

The present invention relates generally to plastic bag manufacture and more particularly to an economical method of mass producing plastic bags which each have a satchel bottom which provides each bag with a neat appearing square shaped bottom when filled.

In the packaging or bagging of bulky products, of which bread is a prime example, it is desirable that the filled bag have a neat, shape-conforming appearance. In the case of bread, this desired shape is, more particularly, square or rectangular and can be provided with a socalled satchel bottom construction, as is commonly provided on paper bags. However, known techniques of applying this construction to paper bags cannot be used in the production of plastic bags without seriously detracting from and interfering with the efiiciency of production or unduly increasing the costs of production of the plastic bags.

Broadly, it is an object of the present invention to provide a method of forming satchel bottom plastic bags which lends itself to economical mass production and which otherwise overcomes the noted and other shortcomings that result in using paper bag manufacturing techniques in the production of this type of plastic bag. Specifically, it is an object to provide a method of bag -manufacturing which contemplates the conversion of conventional bottom gusset bags, which are readily economically mass produced, into the more difficult to produce satchel bottom variety.

An exemplary method of plastic bag manufacture demonstrating objects and advantages of the present invention contemplates, as already noted, using a conventional bottom gusset bag as a starting material. This conventional bag includes, however, as a unique feature an applied body of heat-absorbing material in the apposite ends of the bottom gusset which require removal to complete the conversion to a satchel bottom construction. This removal is achieved by subjecting the bag to a heat source which burns away not only the material but also the plastic, but in so doing does not result in the sealing together of the gusset folds which would prevent the unfolding thereof into the characteristic rectangular configuration of a satchel bottom construction.

The above brief description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred but, nonetheless, illustrative embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front elevational view, with portions broken away, of a plastic bottom gusset bag which is used, in accordance with the present invention, to produce a satchel bottom bag;

FIG. 2 is a bottom plan view illustrating structural features of the bottom gusset;

FIG. 3 is a partial side elevational view, in section taken on line 3-3 of FIG. 1, illustrating still further structural features;

FIG. 4 is a diagrammatic view illustrating the application of heat to the plastic bag which is shown in section taken on line 44 of FIG. 1;

FIG. 5 is a partial front elevational view of the finished satchel bottom bag; and

FIG. 6 is a further front elevational view showing further details of the unattached gusset walls which unfold into the satchel bottom for the bag.

Reference is now made to the drawings, and in particular to FIGS. 1 and 6 respectively showing a work-inprocess plastic bottom gusset bag 10 and a finished satchel bottom bag 10a. The satchel bottom bag 10a, as generally understood, has an inwardly folded bottom gusset 12 characterized by an outer and inner pair of gusset walls 12a and 1212, respectively, which are joined to each other at opposite ends along forty-five degree angled heat seals 14. Also characterizing a satchel bottom construction is the feature that each of the inner gusset walls 12b, while joined to the respective outer gusset Walls 12a at the heat seals 14, are not joined to each other so that when the bag 10a is filled the gusset 12 unfolds into a generally rectangular configuration or bottom for the bag 10a.

Although plastic satchel bottom bags are known, as are also several methods of manufacturing these bags, the present invention is concerned with an optimum method of producing the satchel bottom bag 10a using as an essential and starting work-in-process material the conventional bottom gusset bag 10 as illustrated in FIG. 1. This conventional bottom gusset bag 10 is readily produced by any one of a number of methods since its construction does not present any particular problem. The satchel bottom bag 10a, on the other hand, does present a problem in that it is necessary, as has already been noted, to seal each pair of outer and inner gusset walls 12a, 12b to each other at the heat seals 14 while maintaining the facing inner gusset walls 12b free of attachment to each other, so that unfolding of the gusset 12 can occur to accommodate any materials loaded within the bag 10a.

In accordance with the present invention, the bottom gusset bag 10 includes such conventional features as the usual front wall 16, a rear wall 18, and side welds 20 and 22 joining the front and rear walls to each other to complete the bag 10. It is also contemplated that prior to the application of the side welds 20, 22 that a conventional gusset forming tool will be utilized in a well understood manner to produce an inward fold at the juncture of the front and rear walls 16, 18 to provide the bottom gusset 12. Thus, the bottom gusset 12 includes the usual fold line F, and the two pairs of gusset walls, each of which consists of an outer gusset wall 12a and an inner gusset wall 12b.

In its initial form, as illustrated in FIG. 1, the various gusset walls 12a and 12b constitute a superposed fourply construction which is rectangular in shape and which, therefore, in order to be properly converted into a satchel bottom requires elimination of identical triangular end portions A from the opposite ends of the gusset walls 12a and 12b The elimination of the triangular portions A is readily achieved by applying to the gusset inner walls 12b, or more particularly to portions thereof coextensive with each area to be eliminated, an appropriate heat-absorbing material such as, for example, Sinclair and Valentine fiexographic black ink No. NY74911. This triangular shape of heat-absorbing material A applied, as by printing, on each of the facing gusset walls 12!) includes an inner edge 24 which, at an upper point originates adjacent the side welds 20, 22, as at 24a, and extends therefrom at an oblique angle to a termination point 24b spaced inwardly along the bottom of the gusset. The bottom gusset bag 19 with the applied triangular shapes of heat-absorbing material A are then fed, on a conveyor belt or other such appropriate material transporting apparatus, beneath an external heat source, generally designated 26 in FIG. 4. Once such heat source with which excellent results have been achieved is a General Electric infrared lamp rated at 230-250 volts, 1000 watts. Lamp 26, operated in a well understood manner, is effective to generate sufficient heat which is absorbed by the heat-absorbing bodies A until the burning temperature for the plastic is reached, thereby resulting in a burning away of the areas on the gusset walls 12a, 12b coextensive with each heat-absorbing body A. This is achieved, that is, throughout each entire body A except along the inner edge 24 which remains, due to heat loss or transfer to the adjacent uncoated portions of the inner gusset Walls 1211, at a temperature below the burning temperature of the plastic. As a consequence, a strip of material, designated A in FIG. 6, remains at the interface of the gusset walls 12b, said strip being bounded on one side by the previously noted inner edge 24 and on the opposite side by a line adjacent thereto which is in effect the heat seal 14. The presence of these remaining strips A at their strategic locations in facing relationship along the confronting edges of the inner gusset walls 12b effectively serves as a barrier inhibiting the sealing together of the inner gusset walls 12b. At the same time, each outer gusset wall 12a and inner gusset wall 12b of each pair is effectively sealed to each other along each angled heat seal line 14 during the burning away of each triangular shaped body A of the heat-absorbing material. In this manner a conventional plastic bottom gusset bag 10 having, however, the heat-absorbing bodies A applied in accordance with the present invention is readily converted into a plastic satchel bottom bag 10a.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is ap propriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. A method of producing a plastic satchel bottom bag from a plastic bottom gusset bag of the type having at least a four-ply superposed arrangement of outer and inner gusset walls, the two inner gusset walls of which are in unattached facing relationship permitting said gusset to unfold and provide said satchel bottom for said bag, said method comprising the steps of placing on said inner gusset walls, on their inner facing surfaces, a material of high heat absorption in comparison to the heat absorption of the plastic material forming said bag and forming said high heat absorbing material into a defined pattern at the lower side corners of said inner gusset walls, said defined pattern having an inner boundary along a line extending from a point of intersection of the side of said bag and the upper edge of said gusset walls to a point along the bottom of said gusset walls and spaced inwardly from said side edge, said high heat absorption material being applied in similar patterns to each of the four lower corners of said inner gusset walls, and subjecting said superposed arrangement of gusset walls to external heat to a degree sufficient to cause a melting of the plastic material of said bag underlying said high heat absorbing material and the fusing of said material immediately ad jacent said high heat absorbing material to remove from said bag the areas thereof underlying and overlying said high heat absorbing material and to form fused seal lines adjacent said boundray line whereby the respective inner gusset walls are sealed to their respective outer gusset walls adjacent said broader line and said inner gusset walls are free from sealing attachment to each other and the remaining portion of said high heat absorbing material and the plastic material upon which the same is superposed is removed from said bag leaving a finished satchel bottom bag.

2. The method of producing a plastic satchel bottom bag as defined in claim 1 wherein said pattern is a right triangle.

3. The method of producing a plastic satchel bottom bag as defined in claim 1 wherein said border line is a straight line and is oriented at 45 to the side and the bottom of said bag.

4. The method of producing a plastic satchel bottom bag as defined in claim 3 wherein said defined pattern is triangular.

5. The method of producing a plastic satchel bottom bag as defined in claim 1 wherein said high heat absorbing material is a flexographic ink.

6. The method of producing a plastic satchel bottom bag as defined in claim 5 wherein said ink is applied by printing on the plastic which forms said bag.

7. The method of producing a plastic satchel bottom bag as defined in claim 1 wherein the step of subjecting said arrangement to external heat includes exposing said arrangement to a focused beam of radiant energy from an electrically powered heat source.

8. The method of producing a plastic satchel bottom bag as defined in claim 7 wherein said heat source is an infrared lamp.

References Cited UNITED STATES PATENTS 2,466,966 4/1949 France et al l56-272X 2,480,903 9/1949 Charbonneau 156-272X 2,668,364 2/1954 Colton l56272X BENJAMIN R. PADGETT, Primary Examiner S. J. LECHERT, JR., Assistant Examiner US. Cl. X.R. 

